I'm testing some old computers with CGA and EGA cards. The issue is that I do not have any monitor that support the digital TTL signal, or so I thought.
I own a NEC LCD1990FXp TFT screen that is known to suppoort most analog signals but the manual dosn't mention EGA, CGA or TTL at all. The former owner said the monitor supports every video signal known to man so I thought that it was worth trying to see if it could handle CGA/EGA TTL signals.
To be able to test this a professional CGA/EGA 9pin to "EGA/CGA 15pin" cable is needed.
Well it seems it works! 😀
EDIT
MDA also seem to work with the same cable as I just powered on an early model IBM 5150 (with a black & white / paralell card) that I bought some time ago. I don't think the system has been powered on for ages going by what a total mess the inside of the unit was. This 5150 has been upgraded at some point with a 130W PSU and a Tandon TM502 full height 10MB HDD, sadly the previous owner seems to have forgotten to park it...
Other than the head crash sounding HDD I had a "1010 201" code indicating a faulty memory chip on a memory expansion card. Just reseating some chips in the first row of chips on one of the two memory cards temporarily changed/moved the fault to "1090 201" so it's probably just bad contact.
I also have an intermittent 301 keyboard error and sometimes 131 "cassette port wrap-around" error, could be connected to the memory error.
All in all it's at least not totally dead! 😀
/Edit
Edit2
I fixed the memory issues and could finally boot DOS. 😀
I was too lazy to search extendedly for faulty chips (it seems to be more than one) on the memory cards. I have no manuals for them so I don't know what chip is at what address and so on. I can't even test the memory chips in one of the onboard sockets as they are 64k chips and my 16-64KB motherboard only supports 16k chips. Even if I replace one bank at a time it would still be alot of trial and error as it seems there are faulty chips in more than one bank on each of the two memory cards which holds 192KB and 256KB making the total 512KB.
Luckily I remembered that I have a Lo-tech 1MB memory card and I configured it to fill up from the onboard 64KB to 576KB (544KB).
The "cassette port wrap-around" error seems to have solved it self but the keyboard error is stubborn. The keyboard sort of works but half of the keys are recognized as totally different keys... I think it's a compatibility issue with my clone XT keyboard even if it works just fine with all other XT class systems I have tried.
/Edit2
New PC: i9 12900K @5GHz all cores @1.2v. MSI PRO Z690-A. 32GB DDR4 3600 CL14. 3070Ti.
Old PC: Dual Xeon X5690@4.6GHz, EVGA SR-2, 48GB DDR3R@2000MHz, Intel X25-M. GTX 980ti.
Older PC: K6-3+ 400@600MHz, PC-Chips M577, 256MB SDRAM, AWE64, Voodoo Banshee.